/*
 * Copyright © 2012 The Feign Authors (feign@commonhaus.dev)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package feign.moshi;

import com.squareup.moshi.JsonAdapter;
import com.squareup.moshi.JsonDataException;
import com.squareup.moshi.Moshi;
import feign.Response;
import feign.Util;
import feign.codec.Decoder;
import java.io.IOException;
import java.lang.reflect.Type;
import okio.BufferedSource;
import okio.Okio;

public class MoshiDecoder implements Decoder {
  private final Moshi moshi;

  public MoshiDecoder(Moshi moshi) {
    this.moshi = moshi;
  }

  public MoshiDecoder() {
    this.moshi = new Moshi.Builder().build();
  }

  public MoshiDecoder(Iterable<JsonAdapter<?>> adapters) {
    this(MoshiFactory.create(adapters));
  }

  @Override
  public Object decode(Response response, Type type) throws IOException {
    JsonAdapter<Object> jsonAdapter = moshi.adapter(type);

    if (response.status() == 404 || response.status() == 204) return Util.emptyValueOf(type);
    if (response.body() == null) return null;

    try (BufferedSource source = Okio.buffer(Okio.source(response.body().asInputStream()))) {
      if (source.exhausted()) {
        return null; // empty body
      }
      return jsonAdapter.fromJson(source);
    } catch (JsonDataException e) {
      if (e.getCause() != null && e.getCause() instanceof IOException) {
        throw (IOException) e.getCause();
      }
      throw e;
    }
  }
}
